What’s in a molecule? – the science of macaroni salad from TED-Ed (3m 15s).
Some information on solids, liquids and gases (including a decent animation) can be found here. And this is a video on States of Matter from The Virtual School:
Science Bank 4 (Motion of Particles): Part 1 – Brownian motion (to 4m 45s); Part 2 – Diffusion (to 9m 45s): Part 3 – Changes of State (to 14m 15s):
Not on the syllabus, but interesting: the invisible motion of still objects: